In a known horizontal type blind, a mechanism for opening and closing slats comprises one drive shaft provided in a head box and rotatable by operating an opening and closing cord, a roller fixed to the drive shaft, and two straps for holding side ends of the slats and wound around the roller in such a manner that either on of the straps is fed while the other is taken up according to the rotation of the roller by the opening and closing cord. A mechanism for raising and lowering the slats comprises a roller provided in the head box, extending in a direction perpendicular to the length of the head box and a raising and lowering cord guided through the roller for raising or lowering the slats by the operation of the cord. Since the rollers for opening and closing the slats and for raising and lowering the slats, respectively, are integrally encased in a housing and disposed perpendicularly with each other, their diameters are restricted and cannot be determined freely. In general, to attain accurate opening and closing of the slats and smooth raising and lowering thereof, it is required that the distance between the two hanging straps for holding the slats be small and the diameter of the roller for guiding the raising and lowering cord be large. However, the known mechanism for opening and closing the slats and mechanism for raising and lowering the slats as mentioned above cannot have a structure satisfying the aforesaid requirements. Therefore, the known mechanisms inevitably suffer from defects that the slats are not closed completely and that a considerably large force is required to raise and lower the slats.